Hierachical structure of transition metal cyanide coordination compounds

ABSTRACT

A system and method for implementing and manufacturing a hierarchy system for use with a TMCCC-containing electrically-conductive structure (e.g., an electrode) as well as methods for use and manufacturing of such structures and electrochemical cells including these devices. Structures and methods include a coordination complex having L x M y N z Ti a1 V a2 Cr a3 Mn a4 Fe a5 Co a6 Ni a7 Cu a8 Zn a9 Ca a10 Mg a11 [R(CN) 6 ] b  (H 2 O) c ;. The method includes binding electrochemically active material to produce a hierarchical structure, the hierarchical structure having a plurality of primary crystallites having a size D1, the plurality of these primary crystallites agglomerated into a set of agglomerates each agglomerate having a size D2&gt;D1.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a Division of application Ser. No. 17/711,623 filedon Apr. 1, 2022, the contents of which are hereby expressly incorporatedby reference thereto in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to electrochemical cellsincluding an electrochemically active coordination compound in one ormore conductive structures in such cells, and more specifically, but notexclusively, to an improvement in electrochemical cells having a newclass of transition metal cyanide coordination compounds (TMCCC) foruse, for example, in TMCCC-containing conductive structures, for exampleelectrodes, as well as electrochemical cells made using suchTMCCC-containing conductive structures.

BACKGROUND OF THE INVENTION

The subject matter discussed in the background section should not beassumed to be prior art merely as a result of its mention in thebackground section. Similarly, a problem mentioned in the backgroundsection or associated with the subject matter of the background sectionshould not be assumed to have been previously recognized in the priorart. The subject matter in the background section merely representsdifferent approaches, which in and of themselves may also be inventions.

Electrochemical cells play a critical role in energy storage in avariety of applications including but not limited to electric vehicles,grid storage applications, data center infrastructure, and consumerelectronics. An important property of an electrochemical cell includesan ability to accumulate, hold, and release charge as needed. Theapplication of an electrochemical cell is influenced by discharge ratesat which the cell can be emptied without significant capacity loss andany change in operational characteristics of the cell by theaccumulation, storage, and release of the charge.

FIG. 1 illustrates a Nyquist plot highlighting metrics used inquantification of an electrochemical cell. The Nyquist plot of FIG. 1 isgenerated by electrochemical impedance spectroscopy (EIS) of a cell andprovides an insight into the inner workings of the plotted cell. Theplot includes a semicircle, and the value of the semicircle's interceptwith the real axis (A) is known as the Equivalent Series Resistance(ESR) and is a measure of the internal resistance of the battery. Thewidth of the semicircle (B) is indicative of the charge transferresistance of the electrochemical cell. A larger semicircle width isdetrimental to the performance of an electrochemical cell in that thepower output of the cell is heavily compromised. The 45° slope (C) isindicative of the ionic diffusion through the electrochemical cell.

The Li-ion battery has become a popular battery architecture for mobileapplications such as electric vehicles and portable electronic devicesin part because of the ability of a set of Li-ion batteries to providehigh energy density without sacrificing performance and longevity.However, the increasing cost of Lithium as well as other essentialcomponents of the Li-ion battery have spurred advances into alternative,cheaper options for applications in which high energy density is notrequired.

Sodium is much more abundant than Lithium so in an application and to anextent a sodium-ion battery provides competitive performance as comparedto the Li-ion battery, the sodium-ion architecture may serve as asuitable alternative to Lithium given the proper surrounding framework.Transmission metal cyanide coordination compounds (TMCCC) may besynthesized to create an open framework allowing for high mobility ofSodium ions through the lattice.

Compositions of TMCCC have been described for use in cathode electrodesbut little attention is given to the morphology of the material. Forinstance, REF[1] describes the use of a cathode including a TMCCC havingthe form of A_(x)M1M2(CN)₆, where the A cations may be Na or K, x=0-2,and each of M1 and M2 is a metal cation such as Ti, V, Cr, Mn, Fe, Co,Ni, Cu, Zn, Ca, Mg but does not specify the physical properties of thematerial.

A lack of enforceable physical criteria, opens up the possibility ofcreating TMCCC materials that meet all the desired/requiredcompositional criteria but still underperforms when actually used in anelectrochemical cell.

A first key property is the specific surface area of the TMCCC, asmeasured by Nitrogen adsorption and calculated with theBrunauer-Emmett-Teller (BET) theory, which primarily correlates with theprimary particles size of the TMCCC. As a secondary effect the BET isdecreased with additional aggregation and provides insights into thepores within the material as well as the spacing between aggregates.FIG. 2 illustrates the specific surface area of TMCCC cited in examplesIII, IV, VII, and VIII described herein and the semicircle width ofelectrochemical cells made with those TMCCC. As may be understood from areview of FIG. 2 , when the specific surface area of a TMCCC dropsbeneath a certain point, the semicircle width of an electrochemical cellmade with that TMCCC increases significantly. One popular theory is thata low specific surface area could correspond to inner pores closing offand being inaccessible to ion transfer, thus significantly increasingthe charge transfer resistance. The observation of a significantincrease in the semicircle width as a result of a lower TMCCC specificsurface area, highlights an opportunity for a boundary to be imposed onthe specific surface area of a TMCCC to ensure well performingelectrochemical cells.

The tap density of a TMCCC helps to provide insights into a compactnessof aggregates and a void space between them. FIG. 3 illustrates a tapdensity of the TMCCC cited in the examples described herein, includingexamples III, IV, VI, and VII and the semicircle width ofelectrochemical cells made with those TMCCC. As may be understood from areview of FIG. 3 , when the tap density of a TMCCC increases above acertain point, a semicircle width of an electrochemical cell made withthat TMCCC increases significantly. Such an increase in the semicirclewidth as a result of a lower TMCCC surface area, highlights anopportunity for a boundary to be imposed on the tap density to ensurewell performing electrochemical cells.

A median size of the agglomerates, as measured by a particle sizeanalyzer (PSA) and recorded as the D50, is also preferably consideredand carefully chosen. TMCCC with agglomerates D50 outside of the desiredrange may lead to electrodes with mechanical defects such as cracking ornon-uniform coating. Similarly, the 10th percentile value (D10) and the90th percentile value (D90) must also be limited to a desirably range.

Controlling these physical TMCCC characteristics, including one or moreof tap density, surface area, and D10, D50, and/or D90, may be importantto understanding whether the ensuing electrochemical cell may performadequately and maintain its specific capacity even when discharged at ahigher rate than its nominal rate.

There may be benefits to an appropriately implemented hierarchy systemfor use with a TMCCC-containing electrically-conductive structure (e.g.,an electrode) as well as methods for use and manufacturing of suchstructures and electrochemical cells including these devices.

BRIEF SUMMARY OF THE INVENTION

Disclosed is a system and method for implementing and manufacturing ahierarchy system for use with a TMCCC-containing electrically-conductivestructure (e.g., an electrode) as well as methods for use andmanufacturing of such structures and electrochemical cells includingthese devices. The following summary of the invention is provided tofacilitate an understanding of some of the technical features related toelectrodes including TMCCC materials (and methods for theirmanufacture), and is not intended to be a full description of thepresent invention. A full appreciation of the various aspects of theinvention can be gained by taking the entire specification, claims,drawings, and abstract as a whole. The present invention is applicableto other electrochemically active compounds in addition to TMCCCmaterials, for example other coordination materials, and to otherelectrically-conductive structures that include a coordination material.

An embodiment may include a new class of TMCCC having a coordinationcomplex, having a composition, as synthesized, ofL_(x)M_(y)N_(z)Ti_(a1)V_(a2)Cr_(a3)Mn_(a4)Fe_(a5)Co_(a6)Ni_(a7)Cu_(a8)Zn_(a9)Ca_(a10)Mg_(a11)[R(CN)₆]_(b)(H₂O)_(c); and a plurality of particles of the composition; and whereinthe plurality of particles include a hierarchical structure, and whereinthe hierarchical structure includes a plurality of primary crystalliteshaving a size D1, and in which the plurality of primary crystallites areagglomerated into a set of agglomerates each agglomerate having a sizeD2>D1. One or more of the following may apply: (a) wherein each of L, Mand N represents an alkaline metal; (b) wherein 0≤x≤2; (c) wherein0≤y≤x; (d) wherein 0≤z≤x; (e) wherein 0<b≤1; (f) wherein 0<c; (g)wherein for each element of the set {a1, a2, a3, a4, a5, a6, a7, a8, a9,a10, a11}, 0≤{a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11}≤1; and (h)wherein at least one of {a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11}is >0.

An embodiment for an electrode may include one or more conductivecarbons, one or more polymer binders, a current collector, and one ormore TMCCC; wherein: (a) the conductive carbons include nanoparticulatecarbons; (b) the current collector includes a metal foil; (c) the metalfoil includes a surface coating including carbon; (d) the polymer binderincludes functionalized SEBS binders; and (e) the TMCCC may include acomposition as specified herein.

An embodiment for an electrochemical cell may include a cell stackhaving a liquid electrolyte, an anode electrode, a separator, and acathode electrode, the electrodes electrochemically communicated withthe liquid electrolyte, wherein: (a) the cell stack may containadditional anode, cathode or reference electrodes; (b) the liquidelectrolyte includes a polar organic solvent combined with an alkalimetal salt; (c) the separator includes polymer membranes; (d) themembrane may have a surface coating including nanoparticulate aluminaand boehmite; (e) the anode electrode includes a TMCCC; (f) the anodeelectrode includes a conductive carbon; and (g) the cathode electrodeincludes a TMCCC having a composition as described herein.

An embodiment of the present invention may alternatively include acoordination complex represented by M_(a)N_(b)P_(x)Q_(y)[R(CN)₆]_(z),and may further include a plurality of particles, wherein said particlesinclude a hierarchical structure, and wherein said hierarchicalstructure includes a plurality of primary crystallites having a size D1,and in which said primary crystallites are agglomerated into largeragglomerates having a size D2. Further, wherein one or more of thefollowing apply: (a) wherein each of M and N represents an alkalinemetal; (b) wherein each of P,Q, and R is a metal cation such as Ti, V,Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, Mg; (c) wherein 0<a≤2; (d) wherein0≤b≤a; wherein 0≤x≤1; (e) wherein 0≤y≤1; (f) wherein at least one of xand y is greater than zero; (g) wherein 0<z≤1; (h) wherein D1<1 μm; (i)wherein D2 includes a particle size distribution, in which the 50thpercentile size is greater than 6 μm; (j) wherein the 10th percentilesize of D2 is greater than 1.5 μm; (k) wherein the 90th percentile sizeof D2 is greater than 7.5 μm; (l) wherein the TMCCC material includes aspecific surface area >2 m² per gram; (m) wherein the TMCCC materialincludes a tap density <0.9 g/cm³.

Any of the embodiments described herein may be used alone or togetherwith one another in any combination. Inventions encompassed within thisspecification may also include embodiments that are only partiallymentioned or alluded to or are not mentioned or alluded to at all inthis brief summary or in the abstract. Although various embodiments ofthe invention may have been motivated by various deficiencies with theprior art, which may be discussed or alluded to in one or more places inthe specification, the embodiments of the invention do not necessarilyaddress any of these deficiencies. In other words, different embodimentsof the invention may address different deficiencies that may bediscussed in the specification. Some embodiments may only partiallyaddress some deficiencies or just one deficiency that may be discussedin the specification, and some embodiments may not address any of thesedeficiencies.

Other features, benefits, and advantages of the present invention willbe apparent upon a review of the present disclosure, including thespecification, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer toidentical or functionally-similar elements throughout the separate viewsand which are incorporated in and form a part of the specification,further illustrate the present invention and, together with the detaileddescription of the invention, serve to explain the principles of thepresent invention.

FIG. 1 illustrates a Nyquist plot highlighting metrics used inquantification of a performance of an electrochemical cell;

FIG. 2 illustrates a specific surface area of TMCCC cited in examplesII, V, VI, and VIII described herein and the semicircle width ofelectrochemical cells made with those TMCCC;

FIG. 3 illustrates a tap density of TMCCC cited in the examplesdescribed herein, including examples III, IV, VII, and VIII and thesemicircle width of electrochemical cells made with those TMCCC;

FIG. 4 illustrates a set of discharge curves for the electrochemicalcell from example I at 1 C, 5 C, 10 C and 20 C;

FIG. 5 illustrates a set of discharge curves for the electrochemicalcell from example II at 1 C, 5 C, 10 C and 20 C;

FIG. 6 illustrate a set of discharge curves for the electrochemical cellfrom example III at 1 C, 5 C, 10 C and 20 C;

FIG. 7 illustrates a set of ensuing electrodes made with the TMCCC ofexample X lacking appreciable surface defects;

FIG. 8 illustrates a resulting coat made using the TMCCC of example XI;

FIG. 9 illustrates a charge-discharge cycle of the electrochemical cellmade in example XII, confirming that a functioning electrochemical cellcan be made by pairing a TMCCC cathode electrodes with a PBA anode;

FIG. 10 illustrates a charge-discharge cycle of the electrochemical cellmade in example XIII, confirming that a functioning electrochemical cellcan be created by pairing a TMCCC cathode with a hard carbon anode;

FIG. 11 illustrates a hierarchical structure of the disclosed TMCCCwhich contrasts with the nanoparticulate TMCCC described by REF[2]; and

FIG. 12 illustrates a generic electrochemical cell.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide a system and method forimplementing and manufacturing a hierarchy system for use with aTMCCC-containing electrically-conductive structure (e.g., an electrode)as well as methods for use and manufacturing of such structures andelectrochemical cells including these devices. The following descriptionis presented to enable one of ordinary skill in the art to make and usethe invention and is provided in the context of a patent application andits requirements.

Various modifications to the preferred embodiment and the genericprinciples and features described herein will be readily apparent tothose skilled in the art. Thus, the present invention is not intended tobe limited to the embodiment shown but is to be accorded the widestscope consistent with the principles and features described herein.

Definitions

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this general inventive conceptbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand the present disclosure, and will not be interpreted in an idealizedor overly formal sense unless expressly so defined herein.

The following definitions apply to some of the aspects described withrespect to certain embodiments of the invention. These definitions maylikewise be expanded upon herein.

As used herein, the term “or” includes “and/or” and the term “and/or”includes any and all combinations of one or more of the associatedlisted items. Expressions such as “at least one of,” when preceding alist of elements, modify the entire list of elements and do not modifythe individual elements of the list.

As used herein, the singular terms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to an object can include multiple objects unless thecontext clearly dictates otherwise.

Also, as used in the description herein and throughout the claims thatfollow, the meaning of “in” includes “in” and “on” unless the contextclearly dictates otherwise. It will be understood that when an elementis referred to as being “on” another element, it can be directly on theother element or intervening elements may be present therebetween. Incontrast, when an element is referred to as being “directly on” anotherelement, there are no intervening elements present.

As used herein, the term “set” refers to a collection of one or moreobjects. Thus, for example, a set of objects can include a single objector multiple objects. Objects of a set also can be referred to as membersof the set. Objects of a set can be the same or different. In someinstances, objects of a set can share one or more common properties.

As used herein, the term “adjacent” refers to being near or adjoining.Adjacent objects can be spaced apart from one another or can be inactual or direct contact with one another. In some instances, adjacentobjects can be coupled to one another or can be formed integrally withone another.

As used herein, the terms “connect,” “connected,” and “connecting” referto a direct attachment or link. Connected objects have no or nosubstantial intermediary object or set of objects, as the contextindicates.

As used herein, the terms “couple,” “coupled,” and “coupling” refer toan operational connection or linking. Coupled objects can be directlyconnected to one another or can be indirectly connected to one another,such as via an intermediary set of objects.

The use of the term “about” applies to all numeric values, whether ornot explicitly indicated. This term generally refers to a range ofnumbers that one of ordinary skill in the art would consider as areasonable amount of deviation to the recited numeric values (i.e.,having the equivalent function or result). For example, this term can beconstrued as including a deviation of ±10 percent of the given numericvalue provided such a deviation does not alter the end function orresult of the value. Therefore, a value of about 1% can be construed tobe a range from 0.9% to 1.1%.

As used herein, the terms “substantially” and “substantial” refer to aconsiderable degree or extent. When used in conjunction with an event orcircumstance, the terms can refer to instances in which the event orcircumstance occurs precisely as well as instances in which the event orcircumstance occurs to a close approximation, such as accounting fortypical tolerance levels or variability of the embodiments describedherein.

As used herein, the terms “optional” and “optionally” mean that thesubsequently described event or circumstance may or may not occur andthat the description includes instances where the event or circumstanceoccurs and instances in which it does not.

As used herein, the term “size” refers to a characteristic dimension ofan object. Thus, for example, a size of an object that is spherical canrefer to a diameter of the object. In the case of an object that isnon-spherical, a size of the non-spherical object can refer to adiameter of a corresponding spherical object, where the correspondingspherical object exhibits or has a particular set of derivable ormeasurable properties that are substantially the same as those of thenon-spherical object. Thus, for example, a size of a non-sphericalobject can refer to a diameter of a corresponding spherical object thatexhibits light scattering or other properties that are substantially thesame as those of the non-spherical object. Alternatively, or inconjunction, a size of a non-spherical object can refer to an average ofvarious orthogonal dimensions of the object. Thus, for example, a sizeof an object that is a spheroidal can refer to an average of a majoraxis and a minor axis of the object. When referring to a set of objectsas having a particular size, it is contemplated that the objects canhave a distribution of sizes around the particular size. Thus, as usedherein, a size of a set of objects can refer to a typical size of adistribution of sizes, such as an average size, a median size, or a peaksize.

The TMCCC materials described herein may be used in an electrode in anelectrochemical cell. The electrochemical cell may also includeadditional electrodes, an electrolyte and a separator membrane. Anyadditional electrodes may include a second TMCCC material, a carbonmaterial such as activated charcoal, hard carbon, or graphite, oranother material. The electrolyte may include one or more organicsolvents such as acetonitrile, cyclic or linear carbonates, or otherorganic solvents, or water. The separator membrane may contain polymersand may have surface coating included but not limited to nano-alumina,and boehmite.

As used herein, the term “electrode” in the context of anelectrochemical cell may have different meanings and sometimes encompassdifferent sets of components of the electrochemical cell in differentcontexts and different audiences. For example, the electrode, ascomprised by the TMCCC, carbon, and binder, as well as the solvents usedin the slurry processing to make the electrode, is typically consideredto be entirely separate from a current collector. This electrodestructure could be deposited on any number of current collectors havingdifferent compositions (aluminum, copper, etc.) or mechanical properties(thickness, surface roughness, and the like). One precise definitionwould be to refer to an “electrode” as comprising two components: bothan “active layer” or “electrode composite” including the TMCCC, carbons,and binders, as well as a current collector, which may in turn havesubcomponents such as a special surface coating, or special designfeatures such as physical dimensions. The present application hasadopted a special term used herein to avoid some imprecision that ispresent when referring to an electrode of an electrochemical cell. Thisterm is “electrically conductive structure” and includes electrodes aswell as other electrochemically-active structures that may be used as anelectrode. Some larger structures that encompass an electrode may alsobe such an “electrically conductive structure” within the meaning of thepresent application, unless the context would reasonably suggestotherwise to a person having ordinary skill in the art apprised of thisdisclosure and understanding of the discussion and claims presentedherein.

The current disclosure highlights a new class of TMCCC material with abroad range of specific surface area, tap density and median particlesize. A set of criteria is disclosed which limit the specific surfacearea, tap density and median particles size so as to ensure a lowsemicircle width and the ability to access above 70% of anelectrochemical cell's nominal capacity even when discharging at 20times the nominal discharge rate.

The examples below illustrate an importance of these physical morphologycriteria disclosed as part of embodiments of the present invention.

EXAMPLE I

A TMCCC cathode material having a composition ofNa_(1.24)Mn_(0.78)Fe0.22[Fe(CN)₆]_(0.88)(H₂O)_(2.82) a tap density of0.79 g/cm³, a specific surface area of 4.23 m²/g and D10, D50, D90values of 5.6 um, 8.5 um, 12.9 um respectively, was mixed with anelastomeric adhesive binder and nanoparticulate carbon black in anorganic solvent blend to form a slurry. This slurry was deposited onto acarbon coated aluminum foil current collector using a drawdown coaterand dried at 60° C. for 35 min to evaporate the solvent. The ensuingcoat was calendered (roll pressed) to further increase its density,vacuum dried, and cut into electrodes for use in electrochemical cells.Then, electrochemical cells were assembled by combining a TMCCCelectrode, an activated charcoal electrode, a porous membrane separator,and an electrolyte containing a Sodium(I)Bis(trifluoromethanesulfonyl)imide salt and an acetonitrile solvent.Electrochemical testing of this cell was performed, includingelectrochemical impedance spectroscopy and five constant currentcharge-discharge cycles at a charging rate of 1 C and a discharge rateof 0.2 C, 1 C, 5 C, 10 C, and 20 C.

FIG. 4 illustrates a set of discharge curves for the electrochemicalcell from example I at 1 C, 5 C, 10 C and 20 C. Even at 20 times thenominal discharge rate, the capacity available is above 70% (71.5% of 1C capacity) of the nominal capacity.

EXAMPLE II

A TMCCC cathode having a composition ofNa_(1.18)Mn_(0.77)Fe_(0.24)[Fe(CN)₆]_(0.86)(H₂O)_(2.44) a tap density of0.68 g/cm³, a specific surface area of 1.83 m²/g and D10, D50, D90values of 7.7 um, 12.3 um, 18.1 um respectively, was processed into anelectrode similarly as described in example I. Electrochemical cellswere then made following a similar procedure as in example I.Electrochemical testing of this cell was performed, includingelectrochemical impedance spectroscopy and five constant currentcharge-discharge cycles at a charging rate of 1 C and a discharge rateof 0.2 C, 1 C, 5 C, 10 C, and 20 C.

FIG. 5 illustrates a set of discharge curves for the electrochemicalcell from example II at 1 C, 5 C, 10 C and 20 C. Unlike the cell inexample I, the cell in example II only attains 66% of its nominalcapacity when it is discharged at 20 times its nominal rate.

EXAMPLE III

A TMCCC cathode material having a composition ofNa_(1.25)Mn_(0.75)Fe_(0.25)[Fe(CN)₆]_(0.89), (H₂O)_(2.95) a tap densityof 0.97 g/cm³, a specific surface area of 2.22 m²/g and D10, D50, D90values of 7.3 um, 10.4 um, 14.4 um respectively, was processed into anelectrode similarly as described in example I. Electrochemical cellswere then made similarly to the same procedure as in example I.Electrochemical testing of this cell was performed, includingelectrochemical impedance spectroscopy and five constant currentcharge-discharge cycles at a charging rate of 1 C and a discharge rateof 0.2 C, 1 C, 5 C, 10 C, and 20 C.

FIG. 6 illustrate a set of discharge curves for the electrochemical cellfrom example III at 1 C, 5 C, 10 C and 20 C. Unlike the cell in exampleI, the cell in example III only attains 41% of its nominal capacity whenit is discharged at 20 times its nominal rate.

EXAMPLE IV

A TMCCC cathode material having a composition ofNa_(1.24)Mn_(0.77)Fe_(0.23)[Fe(CN)₆]_(0.88)(H₂O)_(2.57) with a tapdensity of 0.83 g/cm³, a specific surface area of 4.69 m²/g and D10,D50, D90 values of 5.9 um, 9 um, 13.9 um respectively, was processedinto an electrode similarly as described in example I. Electrochemicalcells were then made following similar to the procedure as in example I.Electrochemical Impedance Spectroscopy was then run on these cells.

EXAMPLE V

A TMCCC cathode material having a composition ofNa_(1.25)Mn_(0.79)Fe_(0.21)[Fe(CN)₆]_(0.88)(H₂O)_(3.53) with a tapdensity of 0.83 g/cm³, a specific surface area of 4.71 m²/g and D10,D50, D90 values of 5.9 um, 9 um, 13.5 um respectively, was processedinto an electrode similarly to the manner as described in example I.Electrochemical cells were then made similarly to the procedure as inexample I. Electrochemical Impedance Spectroscopy was then run on thesecells.

EXAMPLE VI

A TMCCC cathode material having a composition ofNa_(1.24)Mn_(0.78)Fe_(0.22)[Fe(CN)₆]_(0.88)(H₂O)_(3.63) with a tapdensity of 0.84 g/cm³, a specific surface area of 3.99 m²/g and D10,D50, D90 values of 6.3 um, 9.4 um, 13.4 um respectively, was processedinto an electrode similarly to the manner as described in example I.Electrochemical cells were then made similarly to the procedure as inexample I. Electrochemical Impedance Spectroscopy was then run on thesecells.

EXAMPLE VII

A TMCCC cathode material having a composition ofNa_(1.17)Mn_(0.75)Fe_(0.25)[Fe(CN)₆]_(0.87)(H₂O)_(2.61) with a tapdensity of 0.57 g/cm³, a specific surface area of 4.69 m²/g and D10,D50, D90 values of 6.7 um, 11.5 um, 17.4 um respectively, was processedinto an electrode similarly to the manner as described in example I.Electrochemical cells were then made following as similar procedure asin example I. Electrochemical Impedance Spectroscopy was then run onthese cells.

EXAMPLE VIII

A TMCCC cathode material having a composition ofNa_(1.15)Mn_(0.75)Fe_(0.25)[Fe(CN)₆]_(0.86)(H₂O)_(2.44) with a tapdensity of 0.68 g/cm³, a specific surface area of 2.96 m²/g and D10,D50, D90 values of 5.6 um, 9 um, 13.5 um respectively, was processedinto an electrode similarly to the manner as described in example I.Electrochemical cells were then made following similarly to theprocedure as in example I. Electrochemical Impedance Spectroscopy wasthen run on these cells.

EXAMPLE IX

A TMCCC cathode material having a composition ofNa_(1.22)Mn_(0.77)Fe_(0.23)[Fe(CN)₆]_(0.87)(H₂O)_(2.50) with a tapdensity of 0.66 g/cm³, a specific surface area of 5.47 m²/g and D10,D50, D90 values of 5.7 um, 10.8 um, 17.2 um respectively, was processedinto an electrode similarly to the manner as described in example I.Electrochemical cells were then made similarly to the procedure as inexample I. Electrochemical Impedance Spectroscopy was then run on thesecells.

Table 1 summarizes a set of physical parameters of the TMCCC in theseexamples as well as a semicircle width of the correspondingelectrochemical cells.

TABLE 1 Specific Semicircle Tap Surface width, density Area D10 D50 D90normalized Example [g/cm³] [m²/g] [um] [um] [um] to Example I 1 0.794.23 5.6 8.5 12.9 1 2 0.68 1.83 7.7 12.3 18.1 3.18 3 0.97 2.22 7.3 10.414.4 5.52 4 0.83 4.69 5.9 9 13.9 2.59 5 0.83 4.71 5.9 9 13.5 1.09 6 0.843.99 6.3 9.4 13.4 1.25 7 0.57 4.69 6.7 11.5 17.4 0.69 8 0.68 2.96 5.6 913.5 0.90 9 0.66 5.47 5.7 10.8 17.2 1.11

Additional examples further highlight an importance of controlling theD10, D50, D90 parameters of the TMCCC to improve post-synthesisprocessing, such as manufacturing a TMCCC that can be processed into anelectrochemical cell with improved characteristics.

EXAMPLE X

A TMCCC cathode material having a composition ofK_(0.63)Na_(0.0045)Mn_(0.72)Fe_(0.28)[Fe(CN)₆]_(0.81)(H₂O)_(2.49), andD10, D50, D90 of 4.9 um, 7.0 um and 9.2 um was mixed with an elastomericadhesive binder and carbon black in an organic solvent blend to form aslurry. This slurry was deposited onto a carbon coated aluminum foilcurrent collector using a drawdown coater and dried at 60° C. for 35minutes to evaporate the solvent. Electrodes were punched out of thecoat using a die punch. FIG. 7 illustrates a set of ensuing electrodesmade with the TMCCC of example X lacking appreciable surface defects.

EXAMPLE XI

A TMCCC cathode material with a composition ofK_(1.18)Mn_(0.80)Fe_(0.20)[Fe(CN)₆]_(0.86)(H₂O)_(5.93) and D10, D50, D90of 1.1 um , 3.6 um and 6.9 um was processed into an electrode similarlyto the manner as in example X.

FIG. 8 illustrates a resulting coat made using the TMCCC of example XI.Contrary to the electrodes seen in FIG. 7 , FIG. 8 depicts severeaggregation on the resulting coat from example XI material. It isbelieved that the severe aggregation may result from the TMCCC havingD10, D50, D90 outside the ranges specified herein as part of a preferredhierarchy. Such aggregation interferes with the TMCCC from beingconverted reliably to electrochemical cells.

The use of the TMCCC proposed is not limited by the choice of anode thatis used when assembling the electrochemical cell. Possible anodes thatcan be paired with TMCCC electrodes include but are not limited to TMCCCelectrodes such as Prussian Blue Analogs (PBA); Carbon Electrodes suchas graphite, hard carbon or activated charcoal electrodes; Antimonybased electrodes; Tin based electrodes; and Silicon based electrodes.The following examples give support for the TMCCC's ability to formfunctional electrochemical cells irrespective of the choice of Anode.

EXAMPLE XII

The TMCCC cathode material described in example I and the TMCCCdescribed in example IX were mixed in a 76:24 ratio. This TMCCC blendwas then mixed overnight with an elastomeric adhesive binder andnanoparticulate carbon black in an organic solvent blend to form aslurry. The ensuing slurry was then coated onto a carbon-coated Aluminumfoil using a slot die coater and then passed through a series of chamberovens. This coat was then calendered (roll pressed) to further increaseits density, vacuum dried, and finally punched into electrodes using amatched metal press to form electrodes. The electrodes were then driedin a vacuum drier to remove moisture in the electrodes. A Honbro Zstacker then created electrochemical cells by weaving the dried TMCCCelectrodes and PBA anode electrodes with a porous membrane separator. Anelectrolyte containing a Sodium(I) Bis(trifluoromethanesulfonyl)imidesalt and an acetonitrile solvent were then added to the cells beforethey were sealed into laminate pouches. The completed cells underwent afull discharge at 1 C followed by a charge-discharge cycle at 1 C. FIG.9 illustrates a 1 C charge-discharge cycle of the electrochemical cellmade in example XII, confirming that a functioning electrochemical cellcan be made by pairing a TMCCC cathode electrodes with a PBA anode.

EXAMPLE XIII

A TMCCC cathode material similar to the one described in example I wasmixed overnight with an elastomeric adhesive binder and nanoparticulatecarbon black in an organic solvent blend to form a slurry. This slurrywas deposited onto a carbon coated aluminum foil current collector usinga frontier coater and dried at 80° C. for 35 minutes to evaporate thesolvent. The ensuing coat was calendered (roll pressed) to furtherincrease its density, vacuum dried, and cut into electrodes for use inelectrochemical cells. The TMCCC electrodes were paired with hard carbonanode electrodes and then assembled into electrochemical cellscontaining a porous membrane separator, and an electrolyte containing aSodium(I) Bis(trifluoromethanesulfonyl)imide salt and an acetonitrilesolvent. The cells were massaged and left to soak overnight to enableimpregnation of electrolyte through the pores before electrochemicaltesting. The cell then went through a charge-discharge cycle at a rateof C/10. The cells then underwent galvanostatic cycling at C/5. FIG. 10illustrates the charge and discharge curves at C/5 for an Example XIIImaterial and demonstrates that a functioning electrochemical cell can becreated by pairing a TMCCC cathode with a hard carbon anode.

REF[2] investigates a role of the particle size of a TMCCC containingcell on its electrochemical performance, however, the reference appearsto have focused on monocrystalline particles of a single chemicalcomposition of TMCCC, KNi[Fe(CN)₆], in a limited range of particle sizesranging from 0.038 um to 0.38 um. Embodiments of the present inventionmay pertain to TMCCC comprising polycrystalline particles in the rangeof 6-20 um. This discrepancy in size indicates a divergence in TMCCCtechnologies; while REF[2] and other art may address nanoparticulateTMCCC, some current embodiments of the present invention involve TMCCCwith a hierarchical structure. In other words, the TMCCC presentlydiscussed is made up of agglomerates of aggregates which in turn consistof the individual crystal. FIG. 11 illustrates a hierarchical structureusing an SEM image of the disclosed hierarchical TMCCC which contrastswith the nanoparticulate TMCCC described by REF[2]. As used herein, theterm “aggregate” is defined as an ellipsoidal cluster of interconnectedTMCCC crystals. As used herein, the term “agglomerate” is defined as acluster of aggregates that have fused or otherwise combined.

For presentation of embodiments of the present invention, the precedingdiscussion of particle hierarchy addresses many implementations. Thereis a nuance in that there may be multiple levels of hierarchy inparticle structure. In a simple case, the primary crystallites are stucktogether into a big particle that is quite dense (it may be thatmicroscope images will not show any pores, and area measurements maydetect just the surface area of the outside of the particle). Therecould also be a case in which the primary crystallites are very denselystuck together into somewhat larger dense “sub-particles”, which in turnare more loosely connected together into an even larger particle. Inthis case, imaging may visualize pores between the sub-particles. Suchparticle hierarchy distributions and implementations are within thescope of the present invention.

FIG. 12 illustrates a generic electrochemical cell 1200. Cell 1200includes a first electrode 1205 (e.g., a cathode electrode), a secondelectrode 1210 (e.g., an anode electrode), a liquid electrolyte 1215, aseparator 1220, a first current collector 1225, and a second currentcollector 1230. One or both electrodes include a coordination compound,and more specifically a transition metal cyanide coordination compound.

REFERENCES

The following references are cited herein, and each of which is herebyexpressly incorporated by reference thereto in its entirety for allpurposes:

REF[1]—U.S. Pat. No. 9,608,268—Alkali and alkaline-earth ion batterieswith non-metal anode and hexacynometallate cathode;

REF[2]—Li et al., Li-ion and Na-ion insertion into size-controllednickel hexacynoferrate nanoparticles, RSC Advances, 2014, 4,24955-24961.

The system and methods above have been described in general terms as anaid to understanding details of preferred embodiments of the presentinvention. In the description herein, numerous specific details areprovided, such as examples of components and/or methods, to provide athorough understanding of embodiments of the present invention. Somefeatures and benefits of the present invention are realized in suchmodes and are not required in every case. One skilled in the relevantart will recognize, however, that an embodiment of the invention can bepracticed without one or more of the specific details, or with otherapparatus, systems, assemblies, methods, components, materials, parts,and/or the like. In other instances, well-known structures, materials,or operations are not specifically shown or described in detail to avoidobscuring aspects of embodiments of the present invention.

Reference throughout this specification to “one embodiment”, “anembodiment”, or “a specific embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention and notnecessarily in all embodiments. Thus, respective appearances of thephrases “in one embodiment”, “in an embodiment”, or “in a specificembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics of any specificembodiment of the present invention may be combined in any suitablemanner with one or more other embodiments. It is to be understood thatother variations and modifications of the embodiments of the presentinvention described and illustrated herein are possible in light of theteachings herein and are to be considered as part of the spirit andscope of the present invention.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Combinations of components or steps will also beconsidered as being noted, where terminology is foreseen as renderingthe ability to separate or combine is unclear.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the Abstract, is not intendedto be exhaustive or to limit the invention to the precise formsdisclosed herein. While specific embodiments of, and examples for, theinvention are described herein for illustrative purposes only, variousequivalent modifications are possible within the spirit and scope of thepresent invention, as those skilled in the relevant art will recognizeand appreciate. As indicated, these modifications may be made to thepresent invention in light of the foregoing description of illustratedembodiments of the present invention and are to be included within thespirit and scope of the present invention.

Thus, while the present invention has been described herein withreference to particular embodiments thereof, a latitude of modification,various changes and substitutions are intended in the foregoingdisclosures, and it will be appreciated that in some instances somefeatures of embodiments of the invention will be employed without acorresponding use of other features without departing from the scope andspirit of the invention as set forth. Therefore, many modifications maybe made to adapt a particular situation or material to the essentialscope and spirit of the present invention. It is intended that theinvention is not limited to the particular terms used in followingclaims and/or to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include any and all embodiments and equivalents falling within thescope of the appended claims. Thus, the scope of the invention is to bedetermined solely by the appended claims.

1-13. (Canceled)
 14. A method manufacturing an electrically conductivestructure for an electrochemical cell, comprising the steps of: a)providing an electrochemically active material including an agglomeratedTMCCC; b) providing a conductive material; and c) binding saidelectrochemically active material to said conductive material producinga hierarchical structure, and wherein said hierarchical structureincludes a plurality of primary crystallites having a size D1, and inwhich said plurality of primary crystallites are agglomerated into a setof agglomerates each agglomerate having a size D2>D1.
 15. The method ofclaim 14 wherein said agglomerated TMCCC includes: a composition ofL_(x)M_(y)N_(z)Ti_(a1)V_(a2)Cr_(a3)Mn_(a4)Fe_(a5)Co_(a6)Ni_(a7)Cu_(a8)Zn_(a9)Ca_(a10)Mg₁₁[R(CN)₆]_(b)(H₂O)_(c);and a plurality of particles of said composition; and wherein saidplurality of particles include a hierarchical structure, and whereinsaid hierarchical structure includes a plurality of primary crystalliteshaving a size D1, and in which said plurality of primary crystallitesare agglomerated into a set of agglomerates each agglomerate having asize D2>D1; wherein each of L, M and N represents an alkaline metal;wherein each of P, Q, and R represents a metal cation optionallyincluding one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, Mg, andthe like; wherein 0≤x≤2; wherein 0≤y≤x; wherein 0≤z≤x; wherein 0<b≤1;wherein 0<c; wherein for each element of the set {a1, a2, a3, a4, a5,a6, a7, a8, a9, a10, a11}, 0≤{a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,a11}≤1; and wherein at least one of {a1, a2, a3, a4, a5, a6, a7, a8, a9,a10, a11} is >0.
 16. The method of claim 15 wherein wherein D1<1 μm. 17.The method of claim 16 wherein D2 includes a particle size distributionhaving a 50^(th) percentile size >6 μm.
 18. The method of claim 17wherein said particle size distribution D2 includes a 10^(th) percentilesize greater than 1.5 μm.
 19. The method of claim 18 wherein saidparticle size distribution D2 includes a 90^(th) percentile size greaterthan 7.5 μm.
 20. The method of claim 15 wherein said compositionincludes a specific surface area >2 m² per gram.
 21. The method of claim19 wherein said composition includes a specific surface area >2 m² pergram.
 22. The method of claim 15 wherein said composition includes a tapdensity <0.9 g/cm³.
 23. The method of claim 19 wherein said compositionincludes a tap density <0.9 g/cm³.
 24. The method of claim 21 whereinsaid composition includes a tap density <0.9 g/cm³.